1. Field of the Invention
The present invention relates to an apparatus and method for detecting foreign particles adhered to a magnetic head of a magnetic tape apparatus, for example.
2. Description of the Related Art
Generally, in a magnetic tape apparatus, a method for detecting contamination or foreign particles adhered to a magnetic head has been suggested to prevent fatal errors from being generated.
In prior art magnetic tape apparatuses, the number of errors or a peak amplitude is detected in recorded signals read from a magnetic tape via a magnetic head, and it is determined whether or not the number of errors or the peak amplitude exceeds a definite value. Only when the number of errors or the peak amplitude exceeds the definite value, is it determined that foreign particles are adhered to the magnetic head to generate a cleaning request signal, so that the foreign particles can be removed by a cleaning operation. This will be explained later in detail.
In the above-described prior art magnetic tape apparatuses, however, if a faulty writing operation is performed upon the magnetic tape, the recorded signals read from the magnetic head may include a large amount of errors or a large peak amplitude even when no foreign particles are adhered to the magnetic tape. As a result, a clearing request signal may be generated so that an unnecessary cleaning operation is carried out, which would waste time.
On the other hand, if a good writing operation is performed upon the magnetic tape, the magnetic head may include a small amount of errors or a small peak amplitude. In this state, even if foreign particles are adhered to the magnetic tape, the number of errors or the peak amplitude may not exceed the definite value, so that a clearing request signal is not generated. Thus, a necessary cleaning operation is not carried out, which would generate fatal errors.
It is an object of the present invention to provide an apparatus and method for effectively detecting foreign particles adhered to a magnetic head.
Another object is to provide a magnetic tape apparatus capable of effectively removing foreign particles adhered to a magnetic head.
According to the present invention, in an apparatus for detecting foreign particles adhered to a magnetic head, a current error rate of data read from the magnetic head is calculated, and an accumulative error rate of data read from the magnetic head is calculated. Then, the current error rate is compared with the accumulative error rate to determine whether or not foreign particles are adhered to the magnetic head.
Also, when it is determined that foreign particles are adhered to the magnetic head, an automatic cleaning signal is generated for automatically cleaning the magnetic head with a cleaning unit or a cleaning request signal for requesting a cleaning operation is sent to the operator.